“…So as not to overload the picture, we plot just the first two iterations and the corresponding points of calculus P t 1 1 , P t 2 1 , and the predicted point P t 3 1 (see Figure 3.4a). Normal method: in order to begin the simulation, the first vector is the normal vector − −−−− → N 1 (P t 1 1 ) to surface α t in point P 1 (x 1 , y 1 ), and in that direction we find the point P j (x j , y j ) i.e P t 2 1 at the intersection with the second contour α t+∆t . Starting from this point in the direction of the normal vector to second contour, we calculate the spatial coordinates of the predicted point (Figure 3.4b).…”